From 52494535103986dbbf689b44d8c2c7efe2132b16 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 14 Nov 2012 16:26:40 -0800 Subject: rcu: Reduce rcutorture tracing Currently, rcutorture traces every read-side access. This can be problematic because even a two-minute rcutorture run on a two-CPU system can generate 28,853,363 reads. Normally, only a failing read is of interest, so this commit traces adjusts rcutorture's tracing to only trace failing reads. The resulting event tracing records the time and the ->completed value captured at the beginning of the RCU read-side critical section, allowing correlation with other event-tracing messages. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett [ paulmck: Add fix to build problem located by Randy Dunlap based on diagnosis by Steven Rostedt. ] diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 275aa3f1..7f89cea 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -53,7 +53,10 @@ extern int rcutorture_runnable; /* for sysctl */ extern void rcutorture_record_test_transition(void); extern void rcutorture_record_progress(unsigned long vernum); extern void do_trace_rcu_torture_read(char *rcutorturename, - struct rcu_head *rhp); + struct rcu_head *rhp, + unsigned long secs, + unsigned long c_old, + unsigned long c); #else static inline void rcutorture_record_test_transition(void) { @@ -63,9 +66,13 @@ static inline void rcutorture_record_progress(unsigned long vernum) } #ifdef CONFIG_RCU_TRACE extern void do_trace_rcu_torture_read(char *rcutorturename, - struct rcu_head *rhp); + struct rcu_head *rhp, + unsigned long secs, + unsigned long c_old, + unsigned long c); #else -#define do_trace_rcu_torture_read(rcutorturename, rhp) do { } while (0) +#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \ + do { } while (0) #endif #endif diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index d4f559b..09af021 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -523,22 +523,30 @@ TRACE_EVENT(rcu_batch_end, */ TRACE_EVENT(rcu_torture_read, - TP_PROTO(char *rcutorturename, struct rcu_head *rhp), + TP_PROTO(char *rcutorturename, struct rcu_head *rhp, + unsigned long secs, unsigned long c_old, unsigned long c), - TP_ARGS(rcutorturename, rhp), + TP_ARGS(rcutorturename, rhp, secs, c_old, c), TP_STRUCT__entry( __field(char *, rcutorturename) __field(struct rcu_head *, rhp) + __field(unsigned long, secs) + __field(unsigned long, c_old) + __field(unsigned long, c) ), TP_fast_assign( __entry->rcutorturename = rcutorturename; __entry->rhp = rhp; + __entry->secs = secs; + __entry->c_old = c_old; + __entry->c = c; ), - TP_printk("%s torture read %p", - __entry->rcutorturename, __entry->rhp) + TP_printk("%s torture read %p %luus c: %lu %lu", + __entry->rcutorturename, __entry->rhp, + __entry->secs, __entry->c_old, __entry->c) ); /* @@ -608,7 +616,8 @@ TRACE_EVENT(rcu_barrier, #define trace_rcu_invoke_kfree_callback(rcuname, rhp, offset) do { } while (0) #define trace_rcu_batch_end(rcuname, callbacks_invoked, cb, nr, iit, risk) \ do { } while (0) -#define trace_rcu_torture_read(rcutorturename, rhp) do { } while (0) +#define trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \ + do { } while (0) #define trace_rcu_barrier(name, s, cpu, cnt, done) do { } while (0) #endif /* #else #ifdef CONFIG_RCU_TRACE */ diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index a2cf761..303359d 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -404,11 +404,14 @@ EXPORT_SYMBOL_GPL(rcuhead_debug_descr); #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ #if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) || defined(CONFIG_RCU_TRACE) -void do_trace_rcu_torture_read(char *rcutorturename, struct rcu_head *rhp) +void do_trace_rcu_torture_read(char *rcutorturename, struct rcu_head *rhp, + unsigned long secs, + unsigned long c_old, unsigned long c) { - trace_rcu_torture_read(rcutorturename, rhp); + trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c); } EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read); #else -#define do_trace_rcu_torture_read(rcutorturename, rhp) do { } while (0) +#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \ + do { } while (0) #endif diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 31dea01..a583f1c 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -46,6 +46,7 @@ #include #include #include +#include #include MODULE_LICENSE("GPL"); @@ -1028,7 +1029,6 @@ void rcutorture_trace_dump(void) return; if (atomic_xchg(&beenhere, 1) != 0) return; - do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL); ftrace_dump(DUMP_ALL); } @@ -1042,13 +1042,16 @@ static void rcu_torture_timer(unsigned long unused) { int idx; int completed; + int completed_end; static DEFINE_RCU_RANDOM(rand); static DEFINE_SPINLOCK(rand_lock); struct rcu_torture *p; int pipe_count; + unsigned long long ts; idx = cur_ops->readlock(); completed = cur_ops->completed(); + ts = trace_clock_local(); p = rcu_dereference_check(rcu_torture_current, rcu_read_lock_bh_held() || rcu_read_lock_sched_held() || @@ -1058,7 +1061,6 @@ static void rcu_torture_timer(unsigned long unused) cur_ops->readunlock(idx); return; } - do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu); if (p->rtort_mbtest == 0) atomic_inc(&n_rcu_torture_mberror); spin_lock(&rand_lock); @@ -1071,10 +1073,16 @@ static void rcu_torture_timer(unsigned long unused) /* Should not happen, but... */ pipe_count = RCU_TORTURE_PIPE_LEN; } - if (pipe_count > 1) + completed_end = cur_ops->completed(); + if (pipe_count > 1) { + unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC); + + do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts, + completed, completed_end); rcutorture_trace_dump(); + } __this_cpu_inc(rcu_torture_count[pipe_count]); - completed = cur_ops->completed() - completed; + completed = completed_end - completed; if (completed > RCU_TORTURE_PIPE_LEN) { /* Should not happen, but... */ completed = RCU_TORTURE_PIPE_LEN; @@ -1094,11 +1102,13 @@ static int rcu_torture_reader(void *arg) { int completed; + int completed_end; int idx; DEFINE_RCU_RANDOM(rand); struct rcu_torture *p; int pipe_count; struct timer_list t; + unsigned long long ts; VERBOSE_PRINTK_STRING("rcu_torture_reader task started"); set_user_nice(current, 19); @@ -1112,6 +1122,7 @@ rcu_torture_reader(void *arg) } idx = cur_ops->readlock(); completed = cur_ops->completed(); + ts = trace_clock_local(); p = rcu_dereference_check(rcu_torture_current, rcu_read_lock_bh_held() || rcu_read_lock_sched_held() || @@ -1122,7 +1133,6 @@ rcu_torture_reader(void *arg) schedule_timeout_interruptible(HZ); continue; } - do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu); if (p->rtort_mbtest == 0) atomic_inc(&n_rcu_torture_mberror); cur_ops->read_delay(&rand); @@ -1132,10 +1142,17 @@ rcu_torture_reader(void *arg) /* Should not happen, but... */ pipe_count = RCU_TORTURE_PIPE_LEN; } - if (pipe_count > 1) + completed_end = cur_ops->completed(); + if (pipe_count > 1) { + unsigned long __maybe_unused ts_rem = + do_div(ts, NSEC_PER_USEC); + + do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, + ts, completed, completed_end); rcutorture_trace_dump(); + } __this_cpu_inc(rcu_torture_count[pipe_count]); - completed = cur_ops->completed() - completed; + completed = completed_end - completed; if (completed > RCU_TORTURE_PIPE_LEN) { /* Should not happen, but... */ completed = RCU_TORTURE_PIPE_LEN; diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 3a35309..7d83f52 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1008,6 +1008,7 @@ config RCU_CPU_STALL_INFO config RCU_TRACE bool "Enable tracing for RCU" depends on DEBUG_KERNEL + select TRACE_CLOCK help This option provides tracing in RCU which presents stats in debugfs for debugging RCU implementation. -- cgit v0.10.2